Plungers are devices used in the oil and gas industry to enhance the recovery of hydrocarbon fluids by reducing a liquid head, which is primarily water. Excessive liquid head and other contaminants can cause a wellbore to slow production, or even cease production altogether. Generally, plungers are periodically and systematically released down a borehole to a predetermined downhole location and then ascend up the borehole, pushing liquid to remove the overall “head” of the fluid column. Sleeves and ribs on the plunger engage the interior surface of the production tubing to extract fluid, gas, and debris as the plunger ascends up the borehole.
Since boreholes may extend thousands of feet below the surface of the Earth, a plunger experiences significant frictional contact with the inner wall of a casing or production tubing. Therefore, plungers frequently wear out, and when plungers wear out, the entire plunger is replaced. Some prior art plungers include replaceable components so the entire plunger is not discarded each time one part of the plunger wears out. Examples of such prior art plungers may be found in U.S. Patent Publication No. 2004/0165992 and U.S. Pat. No. 6,148,923, which are incorporated herein in their entireties by reference.
Another issue with prior art plungers is the inefficient descent speed down the borehole. In a typical configuration, the weight of the plunger overcomes the pressure in the borehole, yet the plunger slowly descends down the borehole. Some prior art plungers have attempted to address this issue with channels or passages that allow fluid to pass through the plunger, thus accelerating the overall “cycle” time that the plunger can be used to enhance production. Examples of such prior art devices may be found in U.S. Pat. Nos. 7,121,335 and 4,410,300, which are incorporated herein in their entireties by reference.
However, no prior art devices address both of these issues simultaneously to provide a plunger that is modular and allows faster descent speeds. There is also a need for a plunger that can deliver chemicals downhole and incorporate electronic devices and sensors for downhole mapping and data collection. These issues, among others, are addressed in the present invention described in detailed below.